Bird-Flu Hunter

GUAN YI

Chances are your shirt, your pants and your underwear all came from southern China, the new manufacturing center of the world. Add one more export: your flu virus. With its dense populations of people and animals trading germs back and forth, southern China has been the traditional birthplace of influenza, including the nasty strain of H5N1 bird flu that's keeping public-health officials awake at night. The viruses that evolve in a chicken in southern China's Guangdong province could eventually end up in your lungs--and that's what makes a chain-smoking, impetuous Chinese virologist named Dr. Guan Yi so important.